There is a constant demand to increase the storage capacity of data systems. As has been set forth in U.S. Pat. No. 6,101,161 issued Aug. 8, 2001, this is especially the case for storing large amounts of data such as, for example, the data required for motion picture images. There are of course a meriad of other needs for data storage, such as storage for library text and other massive amounts of information, which information can for example relate to anything from scientific data to financial data. In the '161 patent, a cylindrical storage medium is indexed rotationally to store holographic image data in the form of pixel arrays generated from a spacial light modulator system (SLM). Multiple holograms are stored in the cylindrical crystal using angular multiplexing by rotating the crystal about its z-axis. Attempts to successfully store and retrieve data from systems such as that of the '161 patent have proved illusive. A primary reason for this is the complicated cylindrical optics for imagery into and out of the cylinder. Another reason for this difficulty is that extraordinarily polarized laser beams appear to be necessary to store holographic gratings in the x, y, plane of cylindrical crystals.
In addition, prior art approaches do not identify a range of angles for angularly positioning each hologram in a cylindrical crystal. Moreover, the prior art does not teach or suggest that a cylindrical crystal may be moved axially in the direction of its c-axis to record holograms at different axial locations in the cylindrical crystal so as to vastly increase the storage capacity of a single cylindrical crystal.